Studies of sources from the WMAP catalog

Observations of a complete sample of sources from the WMAP catalog were obtained at 22.2 and 36.8 GHz on the RT-22 radio telescope of the Crimean Astrophysical Observatory. We have determined the distribution of the source spectral indices between these frequencies. The distributions of the spectral indices of the WMAP catalog (between 23 and 33 GHz) and in the RT-22 sample have the same shape and half-width, suggesting that the mean source parameters are constant in time. We have plotted the log N — log S dependence down to the flux levels of about 0.1 Jy using pilot data from the AT20 survey, where a cosmological “cutoff” in the source counts is already observed. The variability of individual sources in connection with flare activity is considered. The optical characteristics of the complete sample of WMAP sources are compared to those of identified AT20 survey sources.